Arthur Sinodinos insists he has ''no recollection'' of more than $70,000 in donations to the NSW Liberals by his former firm Australian Water Holdings - despite being honorary party treasurer and an AWH director at the time.

As he prepares to appear in the witness box at the Independent Commission Against Corruption on Thursday, Senator Sinodinos seems somewhat forgetful when it comes to giving to the Liberals - or ignorant of the rules.

NSW election funding records show he and his wife Elizabeth personally made payments totalling $1500 to the NSW Liberals in January 2009, just months after he became a director of Australian Water Holdings.

But while the NSW Liberals declared the payments - one of $1040 and another of $460 - as required by law, the Sinodinoses have failed to do so, more than five years later.

Advertisement

On Wednesday a spokeswoman for Senator Sinodinos said it was ''payment of three years' joint membership fees to the Liberal Party of NSW plus a small donation''.

''Membership fees are not declarable and the donation was small and well under the threshold,'' she said. But a NSW Election Funding Authority spokesman said this was not correct. ''Membership fees are considered donations,'' he said. ''Any donation made over $1000 is reportable regardless of whether it represents three years' worth of fees.''

Senator Sinodinos became honorary NSW Liberal treasurer in July 2009, six months after the payments and donation were made.

The ICAC has heard allegations he was installed as an AWH director to open doors to the Liberal Party for the company which was seeking a lucrative public-private partnership with the state government-owned Sydney Water.

The commission has been told that while Senator Sinodinos was an AWH director political donations to the Liberals were billed back to Sydney Water under a loophole in a contract for water infrastructure work in Sydney's north west.

Senator Sinodinos has also insisted he was unaware that Eddie Obeid jnr, the son of corrupt Labor powerbroker Eddie Obeid, worked for AWH.

Upon entering the Senate in October 2011, he said he was shocked to learn of the Obeids' involvement in the company, which the ICAC has alleged extends to a secret one-third shareholding. Shortly after entering Parliament, he was forced to apologise ''unreservedly'' for failing to declare his interests in several other companies, including two private firms and entities related to the Liberal Party.